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What is the bootstrap driver circuit?
The bootstrap circuit uses a coupling capacitor, formed from the gate/source capacitance of a transistor, to drive a signal line to slightly greater than the supply voltage. Some all-pMOS integrated circuits such as the Intel 4004 and the Intel 8008 use that 2-transistor “bootstrap load” circuit.
What is bootstrap driver circuit Why is needed?
The bootstrap circuit is designed to provide a positive voltage bias for the high-side gate driver. When the high-side drivers are active, the reference voltage for the driver will rise close to the bridge supply voltage, VBRG.
Why do you need bootstrap driver for MOSFET?
That’s the whole reason for the bootstrap driver. shortbus, I proved that when an N-Channel MOSFET is used as a high side driver, the gate voltage *needs to be higher than the drain* in my second post. I understand correct, technical explanations – no offence was intended.
How to isolate a high side MOSFET driver?
Capacity of C2 must be chosen enough to supply the driving circuit during the longest on-time. Reverse voltage rating of D1 must be above V High Voltage − V CC. The input signal must be isolated from the boot-strap circuit. Some possible isolaters are: Optocoupler is the most basic method for isolation.
What do you need to drive a MOSFET?
You must drive the MOSFET between its gate and source terminals. Since the source terminal voltage of a high side MOSFET will be floating, you need a separate voltage supply (VBS: V Boot Strap) for the gate drive circuit. In the schematic below, VCC is the voltage source of the rest of the circuit.
Do you need a VBS supply for high side MOSFET driver?
Those grounds must not be directly connected to each other. You must drive the MOSFET between its gate and source terminals. Since the source terminal voltage of a high side MOSFET will be floating, you need a separate voltage supply (VBS: V Boot Strap) for the gate drive circuit.